Correspondences

What is linked, what is not

Each arc joins two phenomena tested on this site. Green and animated: clear link (correlation significant at 5 % after correcting for autocorrelation, or a response outside chance in an event study). Grey: inconclusive test. A statistical link alone does not establish causation.

Clear link
Inconclusive

Hypotheses tested

Clear links

correlation p < 0.05 or epochs outside chance

Causation demonstrated

a correlation demonstrates none

Arc width from |r| of the stored result; several tests between the same phenomena are drawn as stacked arcs.

Hypothesis tested: Tidal stresses are small (a few kPa) but periodic; a detectable modulation of seismicity by the lunar phase is reported for the largest earthquakes only (Ide et al., 2016; Métivier et al., 2009).

Schuster, M 5.5–5.9

0.017

n = 17,658 · p on the simple phase = 0.191

Schuster, M 6.0–6.9

0.139

n = 6,700 · p on the simple phase = 0.102

Schuster, M ≥ 7.0

0.138

n = 742 · p on the simple phase = 0.162

Period analysed

1973 → 2026

computed on Oct 23, 2026 · engine v1.0

Earthquakes by lunar phase

Show the data as a table

Share of earthquakes (%) per 30° bin of Moon–Sun elongation (0° new Moon, 180° full Moon). A uniform distribution gives 8.3% per bin.

Aligned series (CSV)

Method and sources

For every USGS earthquake of magnitude ≥ 5.5 since 1973, the Moon–Sun elongation is computed at the origin time (Meeus, ch. 47 and 25). The Schuster test compares the length of the resultant phase vector with that expected for uniform phases; it is applied to the simple phase and to the doubled phase (which folds new and full Moon, where the tide is largest), by magnitude class.

Computation parameters

{
    "test": "Schuster (Rayleigh) on the phase and on twice the phase (syzygy folding)",
    "phase": "Moon − Sun elongation at the origin time (Meeus ch. 47 and 25)",
    "catalogue": "usgs",
    "from_year": 1973,
    "min_magnitude": 5.5
}

Inputs : usgs.earthquakes.m6.yearly (127 pts, run #158)

Reading this result

A single p-value below 0.05 across three classes and two tests is not a detection; the expected effect is of the order of a few percent and requires declustered catalogues and locally computed tidal stresses, which is not done here. Correlation is not causation: common factors (seasons, cycles, trends) or coincidence can produce it. The p-values account for autocorrelation (effective n) but not for preprocessing choices; the confidence interval comes from a block bootstrap. The limits of the source data apply.

SOURCES OF THIS PAGE

USGS ComCat earthquakes M ≥ 4.5 (FDSN event service): U.S. Geological Survey, Earthquake Hazards Program (2017). Advanced National Seismic System (ANSS) Comprehensive Catalog of Earthquake Events and Products. Accessed through the FDSN event web service. · doi:10.5066/F7MS3QZH · source page ↗
Licence : U.S. Government work, public domain; cite USGS ANSS ComCat · retrieved on Oct 23, 2026 · SHA-256 c1e3c08c2c8f…
Ide et al. (2016): Ide, S., Yabe, S., & Tanaka, Y. (2016). Earthquake potential revealed by tidal influence on earthquake size–frequency statistics. Nature Geoscience, 9, 834–837. · doi:10.1038/ngeo2796
Licence : Published literature; cited
Métivier et al. (2009): Métivier, L., de Viron, O., Conrad, C. P., Renault, S., Diament, M., & Patau, G. (2009). Evidence of earthquake triggering by the solid earth tides. Earth and Planetary Science Letters, 278(3–4), 370–375. · doi:10.1016/j.epsl.2008.12.024
Licence : Published literature; cited

Tides and earthquakes Does the lunar phase trigger earthquakes?

What is linked, what is not